A conventional electric brake device has been known, which is installed in a vehicle wheel and applies braking force to the vehicle wheel by operating an electric motor (for example, see patent document 1). The electric brake device disclosed in the patent document 1 is formed by a small diameter pulley fixed to an output shaft of an electric motor and a large diameter pulley rotatably attached to a body and on which a belt is mounted over onto the small diameter pulley. The large diameter pulley is connected to a two-stage planetary gear set on the common rotation axis and a gear mechanism is formed thereon together with the large diameter pulley.
According to thus structured electric brake device, the driving force of the electric motor is transmitted and rotation speed thereof is decelerated by the transmitting mechanism including the belt and a plural stage planetary gear set and is converted into a translatory movement which is transmitted to a wheel brake device to apply braking force thereto. As explained, since the electric brake device disclosed in the patent document 1 uses a power transmitting mechanism including a belt, the layout of rotation shaft for a gear mechanism is freely designed and the brake device can be easily installed into the vehicle.